4. Playing on the console

4.1 Command-line arguments

Wallyplus supports the following command-line arguments:

• -s n
  Board size n ; usual board sizes are 9 (minimum), 13 or 19 (maximum).
• -handicap m
  Specifies a handicap of m stones for Black. Overridden by -even option.
• -komi p
  Specifies a komi of p for White; note that p is a float.
• -white
  Wallyplus plays white.
• -gtp
  Enters GTP mode (ignores other command-line arguments).
• -h or --help
  Displays a short help file and exits.
• -v or --version
  Shows program name and version and exits.

4.2 Console Output

A 9 x 9 board with a few stones will be displayed as:

        a b c d e f g h j
      1 . . . . . . . . . 1
      2 . . . . . O O . . 2
      3 . . O . . . # . . 3
      4 . . O . . . # . . 4
      5 O O ^ O . . . . . 5
      6 . # O # . # # . . 6
      7 . # # # . . . . . 7
      8 . . . . . . . . . 8
      9 . . . . . . . . . 9
        a b c d e f g h j

where '^' is a ko, '#' is black, 'O' is white.

• Wallyplus prompts for the next move and responds instantaneously.
• Wallyplus expects moves to be typed as LetterNumber (no spaces), e.g. a1 means a stone in the upper left, j9 is bottom right.
• Typing "." (without the double quotes) means an immediate resignation and wallyplus will exit after calculating the final score.
• Typing "pass" will do exactly that. Wallyplus will continue playing or pass, too. If both players pass wallyplus will calculate the final score and exit.

4.3 Strength

• Wallyplus probably ranks around 30 kyu. The algorithm is not very sophisticated and the database of patterns is minimal. The original wally.c was designed as a lightweight, fast Go playing engine.
• Wallyplus is a weak player, but it knows how to play legal moves. This is achieved in 40k of code. By comparison, the implementation of GTP 1.0 in Gnu Go is already 75k long, and it is considered incomplete!
• The main purpose of this program is to serve as a test-bed for a C++ implementation of the Go Text Protocol (GTP). More information on the GTP can be found on the Gnu Go homepage.

4.4 Influence

This uses an influence function that sets up an array EDGE x EDGE in size - it then adds influence as defined by Ryder:

            1
    1   2   5   2   1
    1   6   13  6   1
1   5   13  60  13  5   1
    1   6   13  6   1
    1   2   5   2   1
            1

For friendly pieces (add a negative sign for enemy pieces).

The evaluation uses the opposite absolute value of the place checked (guaranteeing a negative value) - and the greater the number (i.e. furthest from any other piece) is used. This will be used in the beginning of the game (first 10-15 moves). After that the engine reverts to pure pattern matching.